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<pre><span class="sourceLineNo">001</span><a name="line.1"></a>
<span class="sourceLineNo">002</span>/*<a name="line.2"></a>
<span class="sourceLineNo">003</span> * Copyright (C) 2011 Archie L. Cobbs. All rights reserved.<a name="line.3"></a>
<span class="sourceLineNo">004</span> *<a name="line.4"></a>
<span class="sourceLineNo">005</span> * $Id: VaadinExternalListener.html 795 2013-12-11 18:48:15Z archie.cobbs $<a name="line.5"></a>
<span class="sourceLineNo">006</span> */<a name="line.6"></a>
<span class="sourceLineNo">007</span><a name="line.7"></a>
<span class="sourceLineNo">008</span>package org.dellroad.stuff.vaadin;<a name="line.8"></a>
<span class="sourceLineNo">009</span><a name="line.9"></a>
<span class="sourceLineNo">010</span>/**<a name="line.10"></a>
<span class="sourceLineNo">011</span> * Support superclass customized for use by listeners that are part of a Vaadin application when listening<a name="line.11"></a>
<span class="sourceLineNo">012</span> * to non-Vaadin ("external") event sources.<a name="line.12"></a>
<span class="sourceLineNo">013</span> *<a name="line.13"></a>
<span class="sourceLineNo">014</span> * &lt;p&gt;<a name="line.14"></a>
<span class="sourceLineNo">015</span> * Listeners that are part of a Vaadin application should use this superclass if they are going to be registered<a name="line.15"></a>
<span class="sourceLineNo">016</span> * with non-Vaadin event sources, and use the methods {@link #register()} and {@link #unregister()} to control listener<a name="line.16"></a>
<span class="sourceLineNo">017</span> * registration. Subclasses implement {@link #register(Object) register(S)} and {@link #unregister(Object) register(S)}<a name="line.17"></a>
<span class="sourceLineNo">018</span> * to perform the actual listener registration/unregister operations.<a name="line.18"></a>
<span class="sourceLineNo">019</span> *<a name="line.19"></a>
<span class="sourceLineNo">020</span> * &lt;p&gt;<a name="line.20"></a>
<span class="sourceLineNo">021</span> * Use of this class will ensure two things:<a name="line.21"></a>
<span class="sourceLineNo">022</span> * &lt;ul&gt;<a name="line.22"></a>
<span class="sourceLineNo">023</span> *  &lt;li&gt;Events can be delivered {@linkplain ContextApplication#invoke in the proper Vaadin application context}; and&lt;/li&gt;<a name="line.23"></a>
<span class="sourceLineNo">024</span> *  &lt;li&gt;The listener is automatically unregistered from the external event source when the Vaadin application is closed;<a name="line.24"></a>
<span class="sourceLineNo">025</span> *      this avoids a memory leak&lt;/li&gt;<a name="line.25"></a>
<span class="sourceLineNo">026</span> * &lt;/ul&gt;<a name="line.26"></a>
<span class="sourceLineNo">027</span> * &lt;/p&gt;<a name="line.27"></a>
<span class="sourceLineNo">028</span> *<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;p&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> * &lt;b&gt;Important:&lt;/b&gt; subclass listener methods must use {@link #handleEvent handleEvent()} when handling events.<a name="line.30"></a>
<span class="sourceLineNo">031</span> * This will ensure proper locking to avoid race conditions.<a name="line.31"></a>
<span class="sourceLineNo">032</span> * &lt;/p&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> *<a name="line.33"></a>
<span class="sourceLineNo">034</span> * &lt;p&gt;<a name="line.34"></a>
<span class="sourceLineNo">035</span> * Note: when listening to event sources that are scoped to specific Vaadin application instances and already originate events<a name="line.35"></a>
<span class="sourceLineNo">036</span> * within the proper Vaadin application context (i.e., event sources that are not external to the Vaadin application),<a name="line.36"></a>
<span class="sourceLineNo">037</span> * then the use of this superclass is not necessary (however, it also doesn't hurt to use it anyway).<a name="line.37"></a>
<span class="sourceLineNo">038</span> * &lt;/p&gt;<a name="line.38"></a>
<span class="sourceLineNo">039</span> *<a name="line.39"></a>
<span class="sourceLineNo">040</span> * @param &lt;S&gt; The type of the event source<a name="line.40"></a>
<span class="sourceLineNo">041</span> * @see ContextApplication#invoke<a name="line.41"></a>
<span class="sourceLineNo">042</span> * @see VaadinApplicationScope<a name="line.42"></a>
<span class="sourceLineNo">043</span> * @see VaadinApplicationListener<a name="line.43"></a>
<span class="sourceLineNo">044</span> * @see SpringContextApplication<a name="line.44"></a>
<span class="sourceLineNo">045</span> */<a name="line.45"></a>
<span class="sourceLineNo">046</span>public abstract class VaadinExternalListener&lt;S&gt; {<a name="line.46"></a>
<span class="sourceLineNo">047</span><a name="line.47"></a>
<span class="sourceLineNo">048</span>    private final S eventSource;<a name="line.48"></a>
<span class="sourceLineNo">049</span>    private final ContextApplication application;<a name="line.49"></a>
<span class="sourceLineNo">050</span>    private final CloseListener closeListener = new CloseListener();<a name="line.50"></a>
<span class="sourceLineNo">051</span><a name="line.51"></a>
<span class="sourceLineNo">052</span>    /**<a name="line.52"></a>
<span class="sourceLineNo">053</span>     * Convenience constructor. Equivalent to:<a name="line.53"></a>
<span class="sourceLineNo">054</span>     * &lt;blockquote&gt;<a name="line.54"></a>
<span class="sourceLineNo">055</span>     *  {@link #VaadinExternalListener(Object, ContextApplication) VaadinExternalListener(eventSource, ContextApplication.get())}<a name="line.55"></a>
<span class="sourceLineNo">056</span>     * &lt;/blockquote&gt;<a name="line.56"></a>
<span class="sourceLineNo">057</span>     *<a name="line.57"></a>
<span class="sourceLineNo">058</span>     * @param eventSource the event source on which this listener will register<a name="line.58"></a>
<span class="sourceLineNo">059</span>     * @throws IllegalArgumentException if {@code eventSource} is null<a name="line.59"></a>
<span class="sourceLineNo">060</span>     * @throws IllegalStateException if there is no {@link ContextApplication} associated with the current thread<a name="line.60"></a>
<span class="sourceLineNo">061</span>     */<a name="line.61"></a>
<span class="sourceLineNo">062</span>    protected VaadinExternalListener(S eventSource) {<a name="line.62"></a>
<span class="sourceLineNo">063</span>        this(eventSource, ContextApplication.get());<a name="line.63"></a>
<span class="sourceLineNo">064</span>    }<a name="line.64"></a>
<span class="sourceLineNo">065</span><a name="line.65"></a>
<span class="sourceLineNo">066</span>    /**<a name="line.66"></a>
<span class="sourceLineNo">067</span>     * Primary constructor.<a name="line.67"></a>
<span class="sourceLineNo">068</span>     *<a name="line.68"></a>
<span class="sourceLineNo">069</span>     * @param eventSource the event source on which this listener will register<a name="line.69"></a>
<span class="sourceLineNo">070</span>     * @param application the associated Vaadin application<a name="line.70"></a>
<span class="sourceLineNo">071</span>     * @throws IllegalArgumentException if either parameter is null<a name="line.71"></a>
<span class="sourceLineNo">072</span>     */<a name="line.72"></a>
<span class="sourceLineNo">073</span>    protected VaadinExternalListener(S eventSource, ContextApplication application) {<a name="line.73"></a>
<span class="sourceLineNo">074</span>        if (eventSource == null)<a name="line.74"></a>
<span class="sourceLineNo">075</span>            throw new IllegalArgumentException("null eventSource");<a name="line.75"></a>
<span class="sourceLineNo">076</span>        if (application == null)<a name="line.76"></a>
<span class="sourceLineNo">077</span>            throw new IllegalArgumentException("null application");<a name="line.77"></a>
<span class="sourceLineNo">078</span>        this.eventSource = eventSource;<a name="line.78"></a>
<span class="sourceLineNo">079</span>        this.application = application;<a name="line.79"></a>
<span class="sourceLineNo">080</span>    }<a name="line.80"></a>
<span class="sourceLineNo">081</span><a name="line.81"></a>
<span class="sourceLineNo">082</span>    /**<a name="line.82"></a>
<span class="sourceLineNo">083</span>     * Register as a listener on configured event source.<a name="line.83"></a>
<span class="sourceLineNo">084</span>     *<a name="line.84"></a>
<span class="sourceLineNo">085</span>     * &lt;p&gt;<a name="line.85"></a>
<span class="sourceLineNo">086</span>     * This also registers a {@link ContextApplication.CloseListener} on the<a name="line.86"></a>
<span class="sourceLineNo">087</span>     * {@linkplain #getApplication configured Vaadin application} so that when the application<a name="line.87"></a>
<span class="sourceLineNo">088</span>     * closes we can unregister this instance from the event source to avoid a memory leak.<a name="line.88"></a>
<span class="sourceLineNo">089</span>     */<a name="line.89"></a>
<span class="sourceLineNo">090</span>    public void register() {<a name="line.90"></a>
<span class="sourceLineNo">091</span>        this.application.addListener(this.closeListener);<a name="line.91"></a>
<span class="sourceLineNo">092</span>        this.register(this.eventSource);<a name="line.92"></a>
<span class="sourceLineNo">093</span>    }<a name="line.93"></a>
<span class="sourceLineNo">094</span><a name="line.94"></a>
<span class="sourceLineNo">095</span>    /**<a name="line.95"></a>
<span class="sourceLineNo">096</span>     * Un-register as a listener on configured event source.<a name="line.96"></a>
<span class="sourceLineNo">097</span>     *<a name="line.97"></a>
<span class="sourceLineNo">098</span>     * &lt;p&gt;<a name="line.98"></a>
<span class="sourceLineNo">099</span>     * This also unregisters the {@link ContextApplication.CloseListener} registered by {@link #register}.<a name="line.99"></a>
<span class="sourceLineNo">100</span>     */<a name="line.100"></a>
<span class="sourceLineNo">101</span>    public void unregister() {<a name="line.101"></a>
<span class="sourceLineNo">102</span>        this.application.removeListener(this.closeListener);<a name="line.102"></a>
<span class="sourceLineNo">103</span>        this.unregister(this.eventSource);<a name="line.103"></a>
<span class="sourceLineNo">104</span>    }<a name="line.104"></a>
<span class="sourceLineNo">105</span><a name="line.105"></a>
<span class="sourceLineNo">106</span>    /**<a name="line.106"></a>
<span class="sourceLineNo">107</span>     * Get the {@link ContextApplication} with which this instance is associated.<a name="line.107"></a>
<span class="sourceLineNo">108</span>     */<a name="line.108"></a>
<span class="sourceLineNo">109</span>    public final ContextApplication getApplication() {<a name="line.109"></a>
<span class="sourceLineNo">110</span>        return this.application;<a name="line.110"></a>
<span class="sourceLineNo">111</span>    }<a name="line.111"></a>
<span class="sourceLineNo">112</span><a name="line.112"></a>
<span class="sourceLineNo">113</span>    /**<a name="line.113"></a>
<span class="sourceLineNo">114</span>     * Get the event source with which this instance is (or was) registered as a listener.<a name="line.114"></a>
<span class="sourceLineNo">115</span>     */<a name="line.115"></a>
<span class="sourceLineNo">116</span>    public final S getEventSource() {<a name="line.116"></a>
<span class="sourceLineNo">117</span>        return this.eventSource;<a name="line.117"></a>
<span class="sourceLineNo">118</span>    }<a name="line.118"></a>
<span class="sourceLineNo">119</span><a name="line.119"></a>
<span class="sourceLineNo">120</span>    /**<a name="line.120"></a>
<span class="sourceLineNo">121</span>     * Execute the given action using the {@link ContextApplication} with which this instance is associated.<a name="line.121"></a>
<span class="sourceLineNo">122</span>     * Subclass listener methods should handle events using this method to ensure they are handled<a name="line.122"></a>
<span class="sourceLineNo">123</span>     * {@linkplain ContextApplication#invoke in the proper Vaadin application context}.<a name="line.123"></a>
<span class="sourceLineNo">124</span>     *<a name="line.124"></a>
<span class="sourceLineNo">125</span>     * @param action action to perform<a name="line.125"></a>
<span class="sourceLineNo">126</span>     */<a name="line.126"></a>
<span class="sourceLineNo">127</span>    protected void handleEvent(Runnable action) {<a name="line.127"></a>
<span class="sourceLineNo">128</span>        this.getApplication().invoke(action);<a name="line.128"></a>
<span class="sourceLineNo">129</span>    }<a name="line.129"></a>
<span class="sourceLineNo">130</span><a name="line.130"></a>
<span class="sourceLineNo">131</span>    /**<a name="line.131"></a>
<span class="sourceLineNo">132</span>     * Register as a listener on the given event source.<a name="line.132"></a>
<span class="sourceLineNo">133</span>     *<a name="line.133"></a>
<span class="sourceLineNo">134</span>     * &lt;p&gt;<a name="line.134"></a>
<span class="sourceLineNo">135</span>     * Subclass must implement this to perform the actual listener registration.<a name="line.135"></a>
<span class="sourceLineNo">136</span>     *<a name="line.136"></a>
<span class="sourceLineNo">137</span>     * @param eventSource event source, never null<a name="line.137"></a>
<span class="sourceLineNo">138</span>     */<a name="line.138"></a>
<span class="sourceLineNo">139</span>    protected abstract void register(S eventSource);<a name="line.139"></a>
<span class="sourceLineNo">140</span><a name="line.140"></a>
<span class="sourceLineNo">141</span>    /**<a name="line.141"></a>
<span class="sourceLineNo">142</span>     * Register as a listener from the given event source.<a name="line.142"></a>
<span class="sourceLineNo">143</span>     *<a name="line.143"></a>
<span class="sourceLineNo">144</span>     * &lt;p&gt;<a name="line.144"></a>
<span class="sourceLineNo">145</span>     * Subclass must implement this to perform the actual listener registration.<a name="line.145"></a>
<span class="sourceLineNo">146</span>     *<a name="line.146"></a>
<span class="sourceLineNo">147</span>     * @param eventSource event source, never null<a name="line.147"></a>
<span class="sourceLineNo">148</span>     */<a name="line.148"></a>
<span class="sourceLineNo">149</span>    protected abstract void unregister(S eventSource);<a name="line.149"></a>
<span class="sourceLineNo">150</span><a name="line.150"></a>
<span class="sourceLineNo">151</span>// Application close listener<a name="line.151"></a>
<span class="sourceLineNo">152</span><a name="line.152"></a>
<span class="sourceLineNo">153</span>    private final class CloseListener implements ContextApplication.CloseListener {<a name="line.153"></a>
<span class="sourceLineNo">154</span><a name="line.154"></a>
<span class="sourceLineNo">155</span>        @Override<a name="line.155"></a>
<span class="sourceLineNo">156</span>        public void applicationClosed(ContextApplication.CloseEvent closeEvent) {<a name="line.156"></a>
<span class="sourceLineNo">157</span>            VaadinExternalListener.this.unregister();<a name="line.157"></a>
<span class="sourceLineNo">158</span>        }<a name="line.158"></a>
<span class="sourceLineNo">159</span>    }<a name="line.159"></a>
<span class="sourceLineNo">160</span>}<a name="line.160"></a>
<span class="sourceLineNo">161</span><a name="line.161"></a>




























































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